Python中的比较if语句

Question

from pip._vendor.distlib.compat import raw_input

Inventory1 = ["Rice", "Maze", "Oil", "Toothpaste", "Beans", "Cloth", "Pepper"]
print("Here are present items list information:", Inventory1)

CheckInv1 = input('Is this item present in the inventory: \n')

for CheckInv1 in Inventory1:
    if CheckInv1 == ("Rice", "Maze", "Oil", "Toothpaste", "Beans", "Cloth", "Pepper"):
        print("This item is present in the inventory list.")
        break
    else:
        print("User entered item is not present in the list.")
        break

问题：即使在代码输入中输入“Oil”文本，它仍然显示else print语句。 如果语句不进行比较。任何建议。谢谢

Answer 1

很抱歉，此代码全部错误：

1. 覆盖来自input的CheckInv1的值， 因为重复使用循环控制变量的相同名称

2. 测试CheckInv1是否与值的元组相等，但 CheckInv1永远不会是一个元组，所以等式不是 可能的

3. 您将break放在if的两个分支中，因此无论 if条件是否为真，循环将在第一个条件后结束 迭代

你真正需要做的很简单：

Inventory1 = ["Rice", "Maze", "Oil", "Toothpaste", "Beans", "Cloth", "Pepper"]
print("Here are present items list information:", Inventory1)

CheckInv1 = input('Is this item present in the inventory: \n')

if CheckInv1 in Inventory1:
    print("This item is present in the inventory list.")
else:
    print("User entered item is not present in the list.")

Answer 2

您正在尝试将项与元组进行比较。这是不同的类型，因此如果总是被评估为false

if CheckInv1 in ("Rice", "Maze", "Oil", "Toothpaste", "Beans", "Cloth", "Pepper"):

将检查CheckInv1内的内容是否是元组的元素

另外，请注意，您忽略了输入。内部for循环（for CheckInv1 in Inventory1:）CheckInv1是前面定义的Invenory1的一项，而不是用户输入

若您的目的是检查用户输入是否在清单中，那个么应该删除for循环。如果要执行多次，请使用标志（如布尔值）保持循环，只要它的计算结果为true，并要求用户在循环中输入另一个输入：

from pip._vendor.distlib.compat import raw_input

Inventory1 = ["Rice", "Maze", "Oil", "Toothpaste", "Beans", "Cloth", "Pepper"]
print("Here are present items list information:", Inventory1)

CheckInv1 = input('Is this item present in the inventory: \n')
conLoop = True
while conLoop:
    if CheckInv1 in Inventory1:
        print("This item is present in the inventory list.")
        conLoop = False
    else:
        print("User entered item is not present in the list.")
        CheckInv1 = input('Is this item present in the inventory: \n')

此代码不断请求用户输入，直到其中一种产品进入库存